From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Feature suggestion: immediate repair attempt on failed read? Date: Fri, 14 Nov 2008 12:29:25 +0000 Message-ID: <491D6F25.8030301@anonymous.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Linux RAID List-Id: linux-raid.ids On 13/11/2008 23:04, Mikael Abrahamsson wrote (in the "OT: Tips for good hard drives for a home server" thread): > Looking at the md code in linux, would it be possible to do some work > around here in that if a drive read operationstalls, let's try to read > from the other drives and then re-write the block on the drive that > stalled? I'd like to second this suggestion; my coding skills are WAY too rusty to attempt it myself, but it sounds like an excellent idea. We could also have a timeout setting so that if a read stalls, at least the application can get its data (by reading the other discs) and the md subsystem can carry on waiting for the read and/or just doing the rewrite in the background. What happens at the moment - could one slow read cause the array to be switched into degraded mode immediately? Cheers, John.